Inhibition of ion transport across ATII cells by chlorine

Abstract

Lung fluid homeostasis is regulated by ion transport across respiratory and alveolar epithelia. We sought to determine the mechanisms by which chlorine gas (Cl2) exposure damages ion transport of alveolar type II cells resulting in pulmonary edema. Rat ATII cells were cultured under a liquid-liquid interface and an air liquid interface to produce high resistance monolayers. The purity of ATII cells were more than 90% as proved by anti-SP-C staining. Confluent monolayers were covered with 50 μL of lung epithelila lining fluid and exposed to Cl2 (200 ppm for 30 min) which resulted in significant inhibition of total (Isc) and amiloride sensitive (ΔIscam) currents both at 1h and 24 h post exposure. Western blotting studies showed a 20% decrease of total αENaC 24 h post exposure. These changes were at least in part due to activation of mitogen activated kinase ERK1/2 by reactive intermediates: western blotting studies revealed significant increases in the phosphorylated ERK1/2/total ERK1/2 ratio at 1h post exposure. Pre-incubation of ATII cells with either antioxidants or the ERK1/2 inhibitor (U01260) prevented this activation and reversed the decrease of Isc and ΔIscam. In addition, post exposure (1, 8, 21 h) administration of a mixture of low molecular weight scavengers prevented the decrease of ΔIscam 24 h post exposure, attenuated apoptosis. Supported by NIEHS grants 5U01ES015676 and 1U54NS063739.